BRPI1102261A2 - Method of Shaping a Wind Turbine Blade - Google Patents

Abstract

METHOD OF SHAPING A WINDOW TURBINE SHOVEL. The present invention relates to a method of molding a wind turbine blade (1) into a mold (2), which method comprises the steps of applying a film (3) to an internal surface (20) of the mold (2). ; mounting component layers (10) for the wind turbine blade (1) on the film (3); perform curing steps to harden the component layers (10); and subsequently removing the cured wind turbine blade (1) from the mold (2). The invention further describes a film (3) suitable for use in a wind turbine blade molding process, whose film (3) comprises an outer surface (30) for coating a mold (2) and an inner surface (31) for receiving a component layer of wind turbine blade (10) prior to curing, and wherein the inner and outer surfaces (30, 31) of the film (3) are designed to allow complete disengagement of the cured wind turbine blade (1) (2) after curing. The invention also discloses a mold (2) for shaping a wind turbine blade (1) comprising an inner surface (20) suitable for receiving a film such as this (3) and a vacuum extraction outlet (21) for applying a vacuum to extract air from the part between the film (3) and the inner mold surface (20).

Description

Report of the Invention Patent for "METHOD OF SHAPING A WIND TURBINE SHADOW".

The present invention relates to a method of shaping a wind turbine blade, a film for use in a wind turbine blade molding process, and the use of such a film in the molding of a wind turbine blade.

Wind turbine rotor blades can be fabricated using a technique, such as the closed mold casting technique, in which the total blade can be molded. Fiberglass coating material can be used to construct component layers in a suitably shaped mold, and the layers of coating material are bonded with a resin and cured in the mold to give a fiber or plastic reinforced polymer. glass reinforced, generally referred to simply as 'fiberglass'. Such a method is described in EP 1 310 351 A1. To facilitate the release of the finished fiberglass component,

After curing, the mold is usually coated with a release agent, such as a suitable wax so that the resin does not stick to the mold. The release agent is applied to the mold before constructing the glass fiber layers. Known release agents are polyvinyl alcohol, silicone wax, slip wax, etc. The release agent should be applied in a uniform layer, and this layer should be absolutely smooth if the outer surface of the cured blade is also to be smooth. However, it is not easy to apply the release agent so that these requirements are met, and the result may be a rough or wavy component surface. In addition, the types of release agents generally used contain volatile solvents which pose a health risk to anyone exposed to them. However, the main disadvantage of having to use a release agent like this is that after curing, release agent residues can stick to the shovel in certain places. These release agent residues should be removed in a time consuming procedure such as washing or sandblasting, increasing the total cost of manufacture. Therefore, it is an object of the invention to provide an improved way of fabricating a wind turbine blade by molding, overcoming the aforementioned problems.

The object of the invention is achieved by the method of shaping a wind turbine blade according to claim 1, from the film according to claim 9, from the mold according to claim 12 to mold a wind turbine blade , and the use according to claim 14 of a film such as this and a method such as this for molding a wind turbine blade. The method according to the invention of molding a turban blade

A windmill in a mold comprises the steps of applying a film to an internal surface of the mold, assembling component layers for the wind turbine blade over the film, performing curing steps to harden the component layers, and subsequently separating the turbine blade wind cured from the mold.

An obvious advantage of the method is that the film eliminates the need for a release agent so that it is no longer necessary to coat the inner surface (or 'inner surface') of the mold with a release agent. and it is no longer necessary to remove debris from a cured wind turbine blade release agent. In this way considerable savings can be achieved in the manufacturing process without having to use an expensive prepared mold. Instead, a single sheet of film can simply be extended to coat the mold. After curing, the film can be easily separated from the wind turbine blade as explained below.

According to the invention, a film suitable for use in a wind turbine blade molding process comprises an outer surface to coat the inner surface of a mold, and an inner surface to receive a component layer of the wind turbine blade prior to curing, and wherein the inner and outer surfaces of the film are designed to allow complete disengagement of the cured wind turbine blade from the mold after curing. According to one aspect of the invention, the mold for shaping a wind turbine blade comprises an inner or inner surface suitable for receiving such a film, and a vacuum extraction outlet for applying a vacuum to extract air from the part between. the film and the inner surface of the mold.

According to the invention, such a film can be used in the molding of a wind turbine blade using the inventive molding method.

Particularly advantageous embodiments and features of the invention are provided by the dependent claims as shown in the following description. Modality resources may be combined as desired to arrive at additional modalities.

The method according to the invention is particularly suitable for molding large wind turbine blades, which should be lightweight and require a smooth outer surface suitable for paint application. Therefore, in a preferred embodiment of the invention, the component to be molded comprises layers of a suitable material, such as fiberglass or carbon fiber, whose layers are joined with a fiber reinforcement, such as resin, glue, thermoset, etc. Union can be performed in several modes. For example, dry fiberglass coating material may be resin coated during a manual laying step. Alternatively, previously impregnated fiber materials (known as 'prepregs') may be used which are heat cured by applying UV irradiation, etc.

The method according to the invention can be used for any molding technique in which layers are extended into a mold before curing and subsequently removed from the mold. For example, an essentially hollow wind turbine blade can be made by shaping two frame halves which are then joined at the leading and trailing edges by gluing them together. The frame may be provided with additional support by means of one or more beams attached to the inner faces of the frame halves. However, it may be difficult to ensure satisfactory quality of glue joints because of the different material properties - such as modulus of elasticity - of the frame halves and the glue used to join them along their full lengths. . In the case of a wind turbine blade, these glue joints have a potential weakness and may eventually crack or open as a result of the extreme forces acting on the blade. Therefore, in a particularly preferred embodiment of the invention, the mold comprises a closed mold for manufacturing a one-piece wind turbine blade. In the closed mold approach, the fiberglass liner material may be arranged around a core and this structure may then be enclosed in the mold. A fiber reinforcement such as resin or glue may be previously applied or inserted into the mold after it has been closed. After curing, the mold is opened and the wind turbine blade can be removed. Using this approach, it is possible to fabricate a large hollow component, such as a one-piece wind turbine blade and without any potentially critical glue joints.

The film used to coat the mold may comprise any suitable material which does not stick to the cured component layers, whether they comprise resin-filled fiber layers, thermoset plastic layers, prepreg layers, and the like. In a particularly preferred embodiment of the invention, therefore, the film comprises polyethylene, polypropylene, or any other suitable plastic, such as the type of film used to make 'cling film' or 'cling wrap'. One or both surfaces of the film may not have adhering properties, so that the film can be easily removed from the cured wind turbine blade and / or mold. The term 'non-adherent' in the context of a film surface is to be understood that the surface has properties that prevent other materials from sticking to it. For example, the film may comprise a polyvinyl chloride component to reduce the ability of other materials to stick to it. The film used to coat the mold can easily be made to the required width and can be supplied on a roll for convenient dispensing.

Film thickness can determine the uniformity of the extended film layer over the mold. Of course, the film must be flexible enough so that it can coat the mold without forming any wrinkles or folds. On the other hand, the film must be strong enough to allow it to be pulled from the cured component. Therefore, in a preferred embodiment of the invention, the film thickness is at least 20 μιτι and at most 200 μηη, more preferably at most 100 μητι.

As mentioned above, it is desirable for the film to have as smooth a surface as possible, without wrinkles or folds, so that the surface of the molded component will be correspondingly smooth as well. Therefore, in a further preferred embodiment of the invention, the method comprises the step of applying a vacuum between the film and the inner surface of the mold. Vacuum can be applied by dragging air out through a nozzle positioned between the film and the inner surface of the mold. Air extraction from the part between the film and the mold can ensure that the film coats the mold smoothly. The need for vacuum will only be applied until the film is sufficiently 'pressed' into the mold. Then vacuum extraction can be stopped and the component layers can be built into the mold. Of course, if required, vacuum may also be applied during layering of the layers, for example to prevent slippage of the film.

The material and structure of the film used to coat the mold can be chosen according to process requirements. For example, as mentioned above, it is desirable to obtain as flat a surface as possible when vacuuming the part between the film and the mold. However, during vacuum extraction, the film may be sucked into the inner surface of the mold such that small air pockets are formed. Thus, in a particularly preferred embodiment of the invention, the film comprises a relief structure on a film surface applied to the inner surface of the mold. This relief structure may comprise depressions, such as small undulations or raised areas, and may serve to improve the adhesion of the film to the inner surface of the mold during the laying step of the component layers prior to curing. A film that is in direct contact with the inner surface of the mold is preferable to prevent any slippage when the component layers are extended into the mold. Alternatively, the relief structure may comprise a plurality of channels or slots in the film so that a vacuum applied between the film and the inner surface of the mold can optimally drag out any air without allowing any pockets to remain. significant air. Such channels or grooves can easily be formed during film making, for example in an extrusion process, and are preferably arranged such that they are essentially in the same direction as the direction taken by the extracted air, i.e. direction of a vacuum nozzle. In a particularly simple embodiment, the film comprises parallel grooves or channels along its length, and the film is extended longitudinally in the mold, so that vacuum nozzles positioned at each end of the mold can optimally extract any air from the part between. the film and the mold.

Alternatively or in addition to the relief structure on the outer surface of the film, the mold itself can be designed to assist in the vacuum extraction step. Therefore, in a preferred embodiment of the invention, the inner surface of the mold comprises at least one channel for facilitating vacuum removal of air between the film and the inner surface of the mold. Such a channel may be arranged to extend along the length of the mold, across the width of the mold, or in any suitable manner which facilitates air extraction. Preferably, the mold comprises a plurality of channels, and these can be arranged to form or terminate in the vicinity of a vacuum nozzle through which air is drawn out of the part between the film and the inner surface of the mold. After curing and removal of the mold component, the film may

attach to the component. Depending on the properties of the film, it may simply be left over the component to act as an outer layer. However, for some finishing steps, such as painting or varnishing, it may be preferable to perform these over the actual component surface. Therefore, in a further embodiment of the invention, the method comprises the step of separating the film from the component after the component has been removed from the mold, so that the film may be detached from the component. The film may simply be peeled off and discarded, but a sturdy film may be used for re-molding an additional wind turbine blade.

Regardless of whether a vacuum extraction step is used to coat the mold with the film, the film may remain in the mold when the cured component is removed. Then the film can be simply detached from the mold. However, it may be preferred to have the film completely separated from the mold when the paddle is removed after curing. Therefore, in a further preferred embodiment of the invention, the internal mold surface comprises a non-adherent surface or coating. For example, the inner surface of the mold may be coated with a material such as Teflon® which has favorable non-adherent properties.

Other objects and features of the present invention will become apparent from the following detailed descriptions taken in conjunction with the accompanying drawings. It is to be understood, however, that the drawings are intended for illustration purposes only and not as a definition of the limits of the invention.

Figure 1 shows a cross section through an extended component layer mold in a prior art component molding process;

Figure 2 shows a cross section through an extended component layer mold in a component molding process according to the invention;

Figure 3 shows a film according to one embodiment of the invention;

Figure 4 shows a film being separated from a molded wind turbine blade using the method according to the invention. In the drawings, like reference numerals refer to like objects throughout. Objects in diagrams are not necessarily drawn to scale.

Figure 1 shows a cross section through a mold 2 with the component layers extended 10 in a prior art component molding process such as that described in EP 1 310 351 A1, in which a wind turbine blade is formed of the fiber layers 10 and cured in a closed mold 2 in which resin is injected under pressure. Here, mold 2 comprises nozzles 21 through which air can be extracted during a vacuum extraction step, thereby inducing component layers 10 to expand, and whereby glue or resin is drawn in. of component layers 10. To allow the cured wind turbine blade to be removed from mold 2 without damage to its surface, a release agent layer 4 such as silicon wax is applied to the internal surfaces 20 of mold 2, as shown in the enlarged part of the diagram. During removal of the cured shovel from the mold 2, wax residue 4 may remain attached to the outer surface of the shovel 1 and should be removed in an additional step such as washing or sandblasting. Also, before the mold 2 can be reused, the release agent layer 4 must be removed by scraping the inner surface 20 of the mold, or it must be smoothed again to the required level. of uniformity.

Figure 2 shows a cross section through a part of a mold 2 with the extended component layers 10 in a component molding process according to the invention. Essentially, the mold in figure 1 can be used. However, unlike the embodiment shown in Figure 1, instead of treating the inner surface 20 of the mold 2 with a release agent, a film 3 is used to coat the mold 2 as shown in part A of the diagram. For the sake of clarity, because of the relative thicknesses of film 3 and mold 2, only a small region of the overall configuration is shown. The film 3 may be optimally pulled onto the inner surface 20 of the mold 2 by drawing air from the part between the film 3 and the mold 2. For this purpose, as shown in part B of the diagram, a vacuum is applied between film 3 and mold 2, and air is extracted through a vacuum nozzle 21. Then, once mold 2 is satisfactorily coated with film 3, the layers 10 of fiber material (e.g. fiber carbon fiber, fiberglass, prepreg, etc.) can be extended as desired as shown in part C of the diagram. The remainder of the molding process can be carried out in the usual manner, with a vacuum extraction step to pull air out through a vacuum nozzle as shown in Figure 1 to allow the component layers to expand, and a projection. - Curing process to harden the layers. Of course, a single vacuum nozzle can be used for both air extraction steps, and the vacuum nozzle can be designed to penetrate between film 3 and mold 2 for the first extraction step, and to penetrate between film 3 and the component layers 10 for the second extraction step. Part D of the diagram shows section XX 'made through mold 2 and film 3 shown in Part B. Here, the additional channels 22 on the inner surface 20 of the mold allow more efficient extraction of air from the space between the film. 1 through 3 and mold 2. Here, channels 22 are arranged in the direction of vacuum extraction nozzle 21.

Figure 3 shows a cross section through a film 3 according to one embodiment of the invention. Here, film 3 is a thin film 3 of propylene or polyethylene, with a thickness in the range 20 pm to 100 pm. The 'inner surface' 31 of film 3, which will be in contact with the component layers, is preferably flat and smooth. Along its length on the 'outer surface' 32 (i.e., the surface that will be in contact with the inner surface of the mold), the film 3 exhibits the channels 32 or the grooves 32. The film 3 is preferably extended into the mold. such that these slots 32 are in the direction of a vacuum extraction nozzle. In this way, air can be optimally pulled out of the space between the film 3 and the inner surface of the mold during the vacuum extraction step. However, a vacuum extraction step is not absolutely necessary as the film can also be manually pressed into the mold by smoothing it along the direction of the channels. Once the film is satisfactorily compressed or sucked into the mold to provide a favorably smooth surface, the component layers may be extended to form the wind turbine blade as described above on the inner surface 31 of the film 3.

Figure 4 shows a film 3 being separated from a cured wind turbine blade 1 molded using the method according to the invention. As the diagram shows, the film 3 can be easily separated from the cured paddle 1 by simply removing the film 3 as a shell. Assuming that the film 3 has coated the mold to give a smooth, wrinkle-free coating, the surface of the cured shovel 1 is smooth, clean, free of any residue and ready for any finishing steps such as coating. base or paint.

While the present invention has been described in the form of preferred embodiments and variations thereof, it will be understood that numerous modifications and additional variations may be made to this without departing from the scope of the invention. For example, instead of removing the film, a specific film material may be used such that the film may be left on the cured wind turbine blade. For example, if the outer surface of the film has appropriate properties, it may be included in any subsequent finishing steps, such as base coat or paint, and may even serve as a protective function.

For the sake of clarity, it is to be understood that the use of "one" or "one" throughout this application does not exclude a plurality, and "understanding" does not exclude other steps or elements. A "unit" or "module" may comprise several units or modules, unless otherwise noted.

Claims (14)

Method of shaping a wind turbine blade (1) into a mold (2), the method of which comprises the steps of applying a film (3) to an inner surface (20) of the mold (2); - mounting component layers (10) for the wind turbine blade (1) on the film (3); - perform curing steps to harden the component layers (10); and subsequently - removing the cured wind turbine blade (1) from the mold (2). The method of claim 1, wherein the film (3) comprises one or more of the group of polymers comprising polyethylene and polypropylene. A method according to claim 1 or claim 2, wherein the thickness of the film (3) is in the range of 20 μιτι to 200 μπι. A method according to claim 3, comprising the step of applying a vacuum between the film (3) and the inner surface (20) of the mold (2) to extract air from the part between the film (3) and the inner surface. (20) from the mold (2). Method according to any one of the preceding claims, wherein the method comprises the step of separating the film (3) from the wind turbine blade (1) after the wind turbine blade (1) has been removed from the mold. (2). A method according to any preceding claim, wherein the inner surface (20) of the mold (2) comprises a non-adherent coating (20). A method according to any preceding claim, wherein the mold (2) comprises a closed mold (2). A method according to any one of the preceding claims, wherein the step of assembling component layers (10) on the film (3) comprises arranging several layers of glass fibers (10). 9. Film (3) suitable for use in a wind turbine blade molding process whose film (3) comprises an outer surface (30) for coating a mold (2) and an inner surface (31) for receiving a component layer of wind turbine blade (10) prior to the cuff, and wherein the inner and outer surfaces (30, 31) of the film (3) are idealized to allow a complete disengagement of the curing wind turbine blade - from (1) the mold (2) after curing. A film (3) according to claim 9, wherein the outer surface (30) of the film (3) comprises a relief structure. A film (3) according to claim 10, wherein the relief structure on the outer surface (30) of the film (3) comprises several channels (32) or grooves (32). A mold (2) for shaping a wind turbine blade (1), comprising an internal surface (20) suitable for receiving a film (3) as defined in any one of claims 9 to 11, and an outlet of vacuum extraction (21) to apply a vacuum to extract air from the part between the film (3) and the inner mold surface (20). A mold (2) according to claim 12, the inner surface of which (20) comprises at least one channel (22) for facilitating air removal by vacuum extraction of the part between the film (3) and the superimposed surface. - inner surface (20) of the mold (2). Use of a film (3) as defined in any one of claims 9 to 11 in molding a wind turbine blade (1) according to the method as defined in any one of claims 1 to 8.